Everything You Need To Know About Chronic Interstitial Nephritis

If you are one of the six million Americans¹ diagnosed with kidney disease, you probably have many questions. Kidney disease is a complex medical issue that often includes a condition called chronic interstitial nephritis.

Read on for a thorough and understandable explanation of the causes, prevention, and management of chronic interstitial nephritis.

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What is chronic interstitial nephritis?

Although it may seem like complex medical jargon, these three words are easily understood once broken down:

  • Chronic: A medical condition that lasts a long time (weeks, months, or even years) or frequently recurs.

  • Interstitial: Refers to the narrow spaces between or within a human organ. In this case, it refers to the cellular matrix within the kidneys.

  • Nephritis: In medical terminology, "nephr" refers to the kidneys, and the suffix '-itis' means inflammation, so nephritis is defined as inflammation of the kidneys.

When interstitial nephritis comes on suddenly and lasts a short time, the condition is called "acute" instead of "chronic" nephritis.

Whether chronic or acute, interstitial nephritis affects the kidneys, which are a vital part of your body's natural filtration system.

What are the symptoms of interstitial nephritis?

Interstitial nephritis, whether chronic or acute, usually presents one or more of the following symptoms:

  • Back pain

  • Bloating

  • Decreased, or less-than-normal, urine output

  • Impaired concentration

  • Elevated blood pressure

  • Tiredness and/or confusion

  • Low-grade fevers

  • Nausea and/or vomiting

  • Rash

  • Water and salt retention resulting in swelling of the feet, hands, or other body parts

  • Unexplained weight gain

  • Changes in urine color and/or amount

Back pain associated with kidney issues is not the same as the typical lower back pain that occurs from overwork or bad posture. Kidney-related back pain occurs higher and deeper and may progress to the abdomen or groin if left untreated.

What are the causes of interstitial nephritis?

The acute form of interstitial nephritis is typically caused by an adverse or allergic reaction to the medication. More than one hundred prescription and over-the-counter medicines have been associated with nephritis, the most common of which are antibiotics, non-steroidal anti-inflammatory drugs (NSAID), and proton pump inhibitors (PPI) that are used to treat excess stomach acid.

Except for the long-term use of anti-inflammatory tablets, the chronic form of interstitial nephritis is not generally caused by medication. Instead, chronic nephritis is usually associated with other health problems, including but not limited to:

  • Infections elsewhere in the body

  • Lupus, Kawasaki disease, and/or other auto-immune disorders

  • Sarcoidosis (inflammation of the lungs and/or lymph nodes)

  • Elevated blood levels of calcium

  • Elevated blood levels of potassium

When should I see a doctor?

If you experience any symptoms of kidney disease, make an appointment with a doctor right away. In addition to the symptoms of interstitial nephritis outlined above, potential signs of kidney disease may also include:

  • Changes in urine output

  • Chest pain

  • Hard-to-control high blood pressure

  • Itchy, dry skin

  • Loss of appetite

  • Muscle cramps

  • Shortness of breath

  • Sleep issues

Putting yourself in the care of a doctor before kidney disease progresses may prevent a relatively small, treatable kidney condition from advancing to full kidney failure.

How is interstitial nephritis diagnosed?

If, after discussing your detailed medical history, including family history, your healthcare provider suspects kidney issues, you will be asked about any over-the-counter and prescription medications and/or supplements you take. You may even be asked about your use of 'street' drugs. Why? Because adverse reactions to any of these may lead to serious kidney conditions, including chronic interstitial nephritis.

You may be asked to keep a diary outlining how much fluid you drink in a day and how much you urinate. Your physician or healthcare provider will listen to your heart and lungs. Why? Because certain kidney issues, including kidney failure, can be detected by how your breathing sounds through a stethoscope.

Your weight and blood pressure will also be measured because both can increase due to kidney disease.

You will be asked to provide a blood sample that will be put through several tests to evaluate the function of your kidneys. These blood tests may include:

  • Blood creatinine test

  • Blood gas tests

  • Blood urea nitrogen (BUN) test

  • Complete blood count (CBC)

  • Comprehensive metabolic panel

Preparing for your blood tests

Your doctor may request a comprehensive metabolic panel to determine how well your kidneys and liver work. The only discomfort involved with this test is when blood is drawn, and you may develop a slight bruise at the needle site, which will go away soon.

Before your blood panel, you may be asked to not eat or drink liquids for eight hours. If you feel faint afterward, remain seated until the lightheaded sensation goes away.

Depending on the outcome of your blood tests, additional diagnostic tests may be performed, including:

  • Abdominal ultrasound

  • Kidney biopsy

  • Pelvic exam

  • Urinalysis

Urinalysis to detect kidney disease

Used to evaluate liquid waste, urinalysis is a common diagnostic test your doctor may request to check for infection and kidney disease. Unless you are simultaneously scheduled for tests that require fasting, you may eat and drink normally before a urinalysis.

Your urine sample may be taken in a clinical setting, or you may be given a container to fill at home first thing in the morning when urine is most concentrated. In either case, the sample is sent to a lab to evaluate it visually and with a dipstick. Sometimes, urine is also viewed under a microscope.

A urinalysis alone may not provide a definitive diagnosis, but it's an important tool that gives your doctor valuable information they can use to diagnose and treat your kidney condition.

Kidney function tests

There are several tests your doctor may request to evaluate the way your kidneys are, or aren't, functioning². In addition to the blood and urine tests mentioned above, diagnostic kidney imaging tests include:

  • Computerized tomography (CT) scan to evaluate potential kidney damage and/or abnormality

  • Ultrasound imaging to detect tumors, cysts, obstructions, and other kidney issues

Aside from a kidney biopsy, which is pretty much the last resort, kidney function tests are painless and non-invasive. A biopsy is done with an anesthetic, so although it is invasive, there is little discomfort involved with the procedure.

A kidney biopsy can be done with a needle or through an open-and-close incision under local or general anesthesia.

How is chronic interstitial nephritis treated?

If nephritis is caused by an adverse reaction to NSAIDs or other medication, eliminating the problem medication may allow the kidneys to quickly return to normal. Rapid treatment with carefully monitored corticosteroids or more potent immunosuppressant drugs, such as cyclophosphamide, may facilitate complete recovery.

Late diagnosis or failure to follow your doctor's advice may lead to permanent kidney damage that is treated with dialysis.

Dialysis explained

If kidney function tests reveal a condition called end-stage renal disease, or ESRD, dialysis treatment may be the best, and in many cases the only, option. When used to treat interstitial nephritis, dialysis is generally needed for a relatively short period.

Dialysis is meant to replicate kidney function by removing excess fluids and toxins while balancing the body's sodium, potassium, and phosphorus levels. Dialysis allows people with advanced kidney disease to live.

There are two types of dialysis, each of which utilize a dialysate solution in the filtering process and can be done at home with the proper equipment:

  • Hemodialysis circulates the patient's blood through a filtering membrane, called a dialyzer, that sits inside a dialysis machine. After the blood is cleaned, it is returned to the patient's body.

  • Peritoneal dialysis uses the patient's abdominal lining as a filter, and blood is cleaned without ever leaving the body.

Either method can be effective in treating the effects of long-term kidney disease.

Who is at risk of interstitial nephritis?

Several factors may contribute to the risk of developing interstitial nephritis and other kidney-related issues:

  • Diabetes

  • Obesity

  • Cardiovascular (heart) disease

  • Being Native American, Asian, or Black

  • Family history of kidney disease

  • Advanced age

Can chronic interstitial nephritis be prevented?

The chance of developing kidney issues, including stones, urinary tract infections (UTI), and chronic interstitial nephritis, may be lessened by staying hydrated. Sufficient water intake helps your kidneys eliminate toxins while keeping your blood vessels flexible and well functioning.

Other ways to reduce your risk of kidney problems are:

  • Avoiding tobacco in all forms

  • Eliminating excess salt from your diet

  • Enjoying a low-protein diet

  • Exercising daily

  • Limiting the use of NSAID (anti-inflammatory)  medications

  • Maintaining a healthy weight

  • Maintaining healthy blood pressure

  • Monitoring blood sugar levels, if diabetic

  • Taking medications exactly as prescribed

Complications associated with chronic kidney disease

In medical terms, a complication is an unanticipated or unfavorable problem that occurs along with a known problem, such as kidney disease. Chronic kidney disease may lead to issues throughout the body, including but not limited to:

  • Anemia (too few red blood cells)

  • Central nervous system (CNS) damage

  • Decreased immune response

  • Decreased libido (sex drive)

  • Edema (fluid retention)

  • Erectile dysfunction in men

  • Increased risk of bone fractures

  • Metabolic acidosis (too much acid in the blood)

  • Pericarditis (inflammation of the heart)

  • Pregnancy complications

  • Pulmonary edema (fluid in the lungs)

  • Reduced fertility in women

  • Severe or irreversible kidney damage

  • Shortness of breath

  • Sudden rise in blood potassium levels

Anatomy and function of the kidneys and urinary system

The human urinary tract usually comprises two kidneys, two ureters, a bladder, a sphincter, and a urethra. In adults, the reddish-brown, bean-shaped kidneys sit symmetrically on either side of the spine and are around the size of a fist.

Depending on age, gender, height, and body mass index (BMI), a typical adult kidney weighs between 55 and 235 grams. Men's kidneys tend to be heavier than women's, and right-hand kidneys typically weigh more than left-hand ones.

As the digestive system converts food to energy, a by-product called urea is produced. Meats, poultry, and some (but not all) veggies contribute to the production of urea which is carried by the bloodstream to the kidneys by a renal (kidney-related) artery.

Inside each kidney lie minuscule vessels called glomeruli that perform the initial blood filtration before passing the filtered blood into small tubes called renal tubules. These tubules reabsorb water before returning minerals, nutrients, and electrolytes back to the bloodstream. At the same time, urea and other liquid waste are sent to the bladder through a ureter attached to each kidney.

Every day, the human body filters around 200 quarts of blood, removing urea and other toxic waste. Approximately two quarts of urine are excreted a day.

When functioning properly, the kidneys maintain fluid balance and ensure the equilibrium of crucial electrolytes, including potassium and sodium.

What else do kidneys do?

In addition to being effective blood filters, healthy kidneys control blood pH balance, regulate blood pressure, contribute to the production of red blood cells and help your body absorb calcium.

Unfortunately, acute and chronic nephritis makes it difficult or even impossible for kidneys to function as they should. This is why it is important to have it treated early to preserve as much of your kidney function as possible.

The lowdown

Chronic interstitial nephritis is a kidney disorder. It causes inflammation of the spaces between the kidney tubules and affects kidney function. It is usually caused by an underlying health problem.

If you experience any symptoms of the condition, it is important to see a doctor as soon as possible, to prevent the condition from getting worse. Once diagnosed, you may be prescribed medication to help your kidney function improve. If the condition isn't diagnosed for a long time, dialysis may be required.

  1. Kidney disease | Centers for Disease Control and Prevention

  2. CKD diagnosis: Kidney function tests explained | Fresenius Kidney Care

Other sources:

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